1. Field of the Invention
The present invention relates generally to a control circuit for use with an amplifier, and more particularly is directed to a control circuit for use with an amplifier in which even if the amplifier is made operative automatically by a time switch, the amplifier can be made inoperative by a switch, but the amplifier is made operative automatically after a certain time period.
2. Description of the Prior Art
A radio receiver with a timer has been known as an electronic instrument with a timer. With such a radio receiver, it reproduces a received broadcasting wave as a sound at a set time by the timer, or operates its oscillator to produce an alarm sound. Thus, a user can be aware of a predetermined time by the reproduced sound or alarm sound which is utilized, for example, for awakening.
A so-called snooze switch, which operates to stop reproduction of sounds or an alarm once, has also been provided in this kind of electronic instrument. However, even if a user pushes down the snooze switch once after he has awaked to stop the reproduction of sounds from the radio receiver, the radio receiver operates again to produce sounds after a certain time period (for example, about 10 minutes). Then, the user again pushes down the snooze switch to stop the reproduction of sounds from the radio receiver. The user repeats the above operation a number of times (for example, about one hour to ensure that he awakes positively). In practice, since in the prior art the snooze switch turns a power source line on and off, it requires a transistor for a power source switch and another transistor for setting a time which will mean that it requires a number of parts. Further, with the prior art when the radio receiver reproduces sounds after the snooze switch is pushed down, the reproduced sounds are distorted during the transient time period which are offensive.